Programmed fuel injection (PFI) layout Where is the electric fuel pump typically located in a modern PFI system for reliable priming, cooling, and noise reduction?

Introduction / Context:
Most gasoline PFI systems use an electric pump to supply regulated pressure to the fuel rail. Pump placement influences priming, vapor handling, acoustics, and durability.

Given Data / Assumptions:

• Return or returnless PFI layout with an in-line filter and regulator (or in-tank module).
• Need to minimize vapor lock, cavitation, and pump noise.
• Fuel provides cooling and lubrication to the pump.

Concept / Approach:
In-tank placement keeps the pump submerged, ensuring a positive head at the inlet and improved cooling. It also reduces airborne noise and contains any leaks within the tank module. This design has become the industry standard over external frame-mounted pumps for passenger cars.

Step-by-Step Solution:
Identify design goals: priming reliability, NVH control, pump cooling.In-tank pump meets these goals better than engine-bay or external locations.Therefore, the correct location is “in the fuel tank.”

Verification / Alternative check:
Service procedures typically require tank access to replace the pump module; parts catalogs list “in-tank fuel pump.”

Why Other Options Are Wrong:
Filler neck area is not a pump location.

Distributor mount is unrelated to fuel delivery.

Bulkhead and rail-mounted pumps are uncommon in modern PFI due to noise and vapor issues.

Common Pitfalls:
Ignoring fuel filter restrictions and regulator faults that mimic a failing pump; overlooking the fuel pump relay and ground integrity in no-start diagnostics.

Final Answer:
in the fuel tank